i seen in the cpu z, motherboard manufacture not showing anthing in the model it is showing i440BX-SMC60x, i put only one RAM that is 512MB, i can operate computer, computer working fine, if it is bad ram or not ram how can use computer.

The 440BX chipset fully supports 512MB with non-registered RAM and 1GB with registered RAM.http://download.intel.com/design/chipsets/datashts/29063301.pdf
In fact I have two 440BX boards from 1998 that take 1GB RAM.
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No 512MB module will work in a board with the bx chipset.
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128MB modules work as long as they have 8 or more chips.
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256MB modules work if they are low density which means you need modules with 16 chips, each chip organized as 16Mx8. The modules with 16 ram chips organized as 32Mx4 will not work, nor will the modules with 8 chips.

I thought I remembered an old 440BX system with 512MB ... but I checked the two systems I have in my back room that use 440BX (two old Dells -- a 300MHz P-II and a 600MHz P-III); and they both max out at 384MB. Although the chipset supports it, I don't think many consumer desktop boards were made with registered RAM support.

When 440BX first came out 256Mb modules were rare so Intel wouldn't certify the chipset for them.
[Rush to market thing.]
Based on that motherboard manuals were written to say 384MB max if there were 3 slots.
Later on Intel certified 440BX for 256Mb but many mobo manufactures never updated their manuals.
- In other words the specs sheets for your Dells are wrong unless Dell disabled more RAM in the BIOS.
Also as places like Crucial (remember Crucial) go solely on what the mobo manuals say so their info is wrong.

I've taken boards that -say- 384Mb max in the specs sheets (including some laptops with 3 slots) and run 512Mb in them with no problems what so ever. In fact I used one laptop like that for about 4 years.
The only snag I can think of is on 3 slot boards where if you mix a 256Mb (which is double sided) with two single sided 128MB modules things might not work so well.

Also the restriction to 512Mb is over Intel's concern for signal integrity. - It's not really a limit.
Intel just didn't think it would work well so they didn't approve the configuration.
-yet- They did it with their own boards...
This one uses unregistered RAM on a 440BX up to 768Mb.http://download.intel.com/design/motherbd/oem/72698401.pdf

The chipset has a map of memory addresses (bits) in the RAM.
The map has width and depth and so on paper it has a shape.
(That's why they call it a map.)
The width and depth are about the same thing as latitude and longitude in that they identify locations.
Those locations are bits.

The construction of a RAM module gives the bits in it a width and depth too.

The chipset can only access memory when the shape of the memory fits inside the shape of the chipset's map. If any bits are outside of the chipsets map then it can't use that memory because it doesn't know where the bits are.

In the picture:
- the two dark blue boxes show the shape of chipset's memory map. The width of each box is 64 bits.
- the four purple boxes show the shape of the 512Mb module. The width of each box is 32 bits.
The chipset can only 'see' RAM where the boxes overlap. (The light blue shaded area.)

As willcomp noted, you need double-sided 128MB modules. I just confirmed that both of my 440BX systems have 3 128MB double-sided modules (thus have 384MB installed). I've tried single-sided 128MB modules in the past, as well as both single and double-sided 256MB modules; and none of these work [Just for grins, I just booted up the old XPS-D300 and tried a single-sided 128MB module to confirm my recollection was correct -- it indeed does not work.]

But PCBonez is also correct that Intel provided support for 3 256MB modules on their implementation of a 440BX motherboard -- although it still required modules with an x64 organization (otherwise 256MB modules would simply be "seen" as 128MB).

While the 440BX chipset documentation does indeed make it clear that it CAN support more with registered modules; I've never seen a consumer board using it that supported registered RAM. I'm sure there were some (PCBonez apparently has one); but I've not encountered them.

... While this discussion is interesting (and brings back a few memories of older systems), the bottom line for this question is simple: You need to get double-sided 256MB modules if you want to increase your memory.

I agree that most consumer boards say they are limited to 384MB and that some actually are but I think the limit is imposed by the BIOS implementation.
I suspect that someone [a lot smarter then me] could rewrite the BIOS code to utilize all the RAM the BX chipset is capable of.

I suspect the board will run 2x256Mb double sided modules without a hitch.

Given we don't -really- even know what this board is, it's hard to say.

A 440BX will not run unbuffered 256MB modules unless they have 32 64MBit chips. There were such modules, but they were rare and expensive. As previously stated, the 440BX memory controller is limited to 64MBit chips.

Just for grins, I thought I'd try a 256MB double-sided module in the XPS-T650 (I thought I had a double-sided 256MB module in my "stash") ... but I could only find a single-sided one (may have given away the double-sided one). I'll take a more detailed look later this evening, and if I can find it will confirm whether or not it works.

The 256Mb double sided modules are again Crucial CT32M64S4D7E.16T [16 chips]
The 256Mb single sided modules are Micron MT8LSDT3264AG-133C2 [8 chips]
The 512Mb is generic Samsung low density I used to use in an i845 chipset board. [16 chips]

Assuming the asker's BIOS was updated to support 256Mb modules they will work fine.
The hardware supports it.
.

There are two issues in this discussion: (a) Whether or not the board supports 256MB modules -- PCBonez correctly noted that it does [and offered several pictorial proofs :-) ]; and (b) why the 512MB modules only indicate 128MB is installed -- both PCBonez and I noted that this is a memory density issue (PCBonez also gave a nice explanation of the reason it was 1/4th of the memory).

PCBonez clearly spent more time providing detailed diagrams that hopefully helped with the understanding of the question. I'd suggest 400 points for PCBonez (with http:#a24071191 as the Accepted answer) and 100 for me (http:#a24073080).

Note there were quite a few incorrect comments by several of us during this discussion -- PCBonez, willcomp, and myself all made comments that, on reflection (and perhaps checking some of our old systems) we found were not correct :-) Just shows the value of an ongoing dialogue !!

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